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N. TESTRUP AND T. RIGBY. av-rnooucr RECOVERY mom GAS PRODUCERS AND WE LIKE.

APPLICATION HLED IMR. I. HIB.

1 ,3 1 6,3 39. Patented Sept. 16, 1919.

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UNITED STATES PATENT OFFICE.

NIIS TESTBUP, OF WESTMINSTER, LONDON, ENGLAND, AND THOMAS RIGIBY, 0F DUMFRIES, SCOTLAND.

BY-PRODUCT RECOVERY FROM GAS-PRODUCERS AND THE LIKE.

Specification of Letters Patent.

Patented Sept. 16, 1919.

Application filed March 7, 1916. Serial No. 82,656.

1 '0 all 'UJ/LOHL it may concern:

Be it known that we, Nins Tns'rnnr, a subject of the King of Great Britain and Ireland, and residing at 3 Dean iFarrar street, Westminster, London, S. W., England, and THOMAS Riser, a subject of the King of Great Britain and Ireland, and residing at 61 Loreburn street, Dumfries, Scotland, have invented certain new and useful Improvements in and Relating to By-Product Recov cry from Gas-Producers and the like, of hich the following is a specification.

This invention relates to the recovery of by-products in the gasification of peat, coal and other fuels in gas producers and the like having a distillation and a combustion zone.

In such processes, the tar is usually separated from the liquor and sold, to be there after worked up by tar distillers, who distil off various oils and obtain pitch as a residue. In the majority of cases such itch contains about half its weight of vo atile matter, while the harder varieties contain as much as 30 to 40 per cent. thereof. Hitherto it has not been practicable to obtain itch of a good quality containin none of suc volatile matter, as further co ing of the material in the stills requires such a high temperature as to produce decomposition of the pitch, and render the stills liable to damage.

We have found, however, that the pitch, whether of the medium or hard quality, can be readily distilled without the over cracking of the gases and deposit of fixed carbon accompanyln distillation in a retort b introducing it into a producer along wit the ordinary raw fuel supply thereto, and that the greater portion of the volatile matter is then given off as an oil-bearing tar, and is recovered with the tar emanating from the raw fuel itself. In this way, theamount of tar recovered from the producer and the quantity of oil obtained from the tar stills is proportionately increased, while the nonvolatile portion of the pitch consisting mainly of carbon is converted first to carbon dioxid and then reconverted into carbon monoxid in the lower part of the producer until nothing remains but ash, which is discharged in the usual manner. By thus utilizing the pitch, the revenue from by-products is substantially increased.

It is to be understood that the invention does not relate to the distillation of pitch in closed or like retorts in which no subsequent combustion of the residual carbon and other substances is effected, nor does it apply to the spraying of liquid pitch directly into the combustion zones of gas producers or furnaces.

The invention consists, therefore, in distilling the residual pitch from the tar stills in the distillation zones of a solid fuel body such as that of a producer.

The invention also consists in the process for the utilization of peat in which the peat tar is distilled, and the residual pitch passed directly into the gas producers, from which the power needs of the process are supplied.

The invention further consists in the improved mcthods for distilling pitch as hereinafter described.

In the arrangement shown by way of example in the accompanying drawing, the tar is distilled in the still A and the pitch is run cfi into pitch cooling ponds B. After cooling, the pitch is broken in the pitch breaker C and conveyed by means of a suitable elevating or conveying device D to bunkers E, whence it is fed in measured quantities by means of a measuring device F into a hopper H over the gas producer J. The fuel is fed by means of the elevating device K, hopper E and measuring device F into the producer hopper H, the speeds of the two measuring machines being preferably set so that the mixture in the hopper H contains fuel and pitch in definite proportions. The mixed pitch and fuel is then fed into the producer J and the volatile constituents of the pitch are distilled by the heat of the producer gas in the distillation zoneof the producer J passing over with the producer gas into the tar washer L whence these products are washed out from the ases which then pass away by means of t e main M for use.

The carbon constituents of the pitch pass downward into the combustion zone of the producer where they are gasified together with the carbon of the fuel.

When operating in accordance with the invention care must be taken in the arrangement that the itch is completely distilled before the resi ue reaches the zone of combustion and in order to achieve the foregoing result the pitch is mixed as intimately as possible with the fuel, either in the manner described or in the liquid form by spraying. In the former case, the pitch is preferably broken into pieces about the size of an cg or of such size as to be uniform with the patijcles of fuel by which the gas producer 13 e The depth of the gas producer is pref erab'ly so arranged that the distillation of the pitch is complete before the residue reaches the combustion zone, which results in a high proportion of the volatile matter distilled from the pitch being carried forward in the producer gas as eondensable products. The final result is that the tar, which is condensed from the gas in the tar extracting apparatus gives a higher yield of oil than is produced under ordinary conditions. Consequently when such tar is distilled in the distillation plant, a much higher proportion of oil is given off than is the case with tar normally produced from the fuel.

It has been found that the tar deposited in the various parts of the tar recovery a pparatus of the (producer plant, is of a more oily nature an has the additional advan tags that in an ammonia recovery plant of this type, the oily nature of the tar washes and purifies the sulfate liquor.

The tar so recovered from the sulfate liqnor tanks is in a thinner condition than usual, and is therefore more easily separated from the sulfate liquor, and with a much less loss of sulfate than is the case under ordinary conditions.

It will be seen that many other advantages besides increased yield of oil are obtained by this process, and it is found that the quantity of pitch which can *be fed to the producer may be varied within Wide limits without detriment, although a constant rate of feed should preferably be maintained when once fixed upon, so that the fuel proper may be intimately mixed in regular proportions with the pitch.

When working with pea/t fuel the tar normally roduced gives off about 50 per cent. oil in d sti1lation,'45 per cent. being pitch and 5 per cent. being wasted by decomposition, &c., in the distillation. The addition of this pitch to the producer in this cycle of operations results in the fact that nearly onehalf as muchfloil again is produced. This means that from 100 parts of tar (calculated dry) parts of oil as end product are obtained. It is also found that the nitrogen in the pitch after distilling in the producer is higher than in the original fuel from which the pitch came. In one case in which the fuel contained 1 per cent. nitrogen, the pitch coke after istillation by this system showed 2 per cent. nitrogen with the result that in an ammonia, recovery gas reducer, the yield of ammonia is greater rom this than firom a corresponding weight of normal fuel.

When working with coal, in one case, the tar normally produced gave on distillation 20 per cent. of the original bulk of tar (calculated dry) as oil, per cent. being pitvh and the remainder being lost in decomposition in the stills. When this pitch is fed to the gas producer in the correct ratio it is found that the yield of oil per ton of tar (wlculated dry) becomes appi'o-ximately from 50 per cent. to 55 per cent. of the original weight of tar, the remaining 45 per cent. being gasifiial as pitcl'i-coke in the gas producer in the usual manner.

In the case of blast furnaces using coal, the same principles may be applied as above, and the oil yield correspondingly increased with the result that there is no pitch containing large percentages of ash to be disposed of, and the utilization of the fuel value of the pitch-coke means a saving in the amount of fuel used in the blast furnace, while at the same time the more valuable commodity, oil, is produced in correspondingly greater quantities.

In feeding pitch into the blast furnace it may be fed in. intii'nate admixture with the other chargin materials or the pitch may in the first [)filf't. be amalgamated with any of the ingredients of the charge for the furnace, care being exercised that it is introduced in such a manner that the whole of the volatile matter has been distilled from the pitch in the distillation zone before the residue can reach the zone of combustion. This applies in all cases, whether to blast furnace or gas roducer apparatus, as it has been found that if the pitch is allowed to reach the combustion zone it is burnt and consumed to gases instead of forming oil, as mi ht be expected.

In t e case of gas producers in which the fuel is more or less caking and in which there is a. tendency for cracks, to form in the fire, it is preferred that the pitch be fed into the producer in such a manner that it tends to remain largely in the center part of the producer as by this means there is not the same tendency for the pitch when it becomes liquid to run through the cracks to the combustion zone, the pitch not being in active contact With the producer gases being made, and being more or less distilled in the more stagnant parts of the fuel bed.

Having now described our invention, what We claim as new and desire to secure by Let ters Patent, is w I. A method of utilizing pitch consisting in gasifying the volatile and non-volatile constituents thereof in a gas producing chamber through which it moves to successively hotter zones in admixture with other matter such as fuel and in the reverse direction to air admitted to said chamber.

2. A method of utilizing pitch consisting in gasifying the volatile and non-volatile constituents thereof in successive tempera ture zones of a. gas producing chamber to which it is fed in admixture with other matter such as fuel, said chamber being heated by partial combustion of part of the mixture.

3. A method of utilizing pitch consisting in gasifying the volatile and non-volatile constituents thereof in successive temperature zones of a gas producing chamber heated by partial combustion therein of the non-volatile portions of said pitch and other fuel with which it is mixed.

4. A method of utilizing pitch consisting in feeding said pitch homogeneously mixed with other matter such as fuel to the upper portion of a furnace chamber, distilling said pitch by the heat of gases generated by combustion taking place under regulated air supply in the lower portion of said chamber and finally completing the combustion of said pitch in said lower portion of the chamber.

5. A method of utilizing pitch consisting in incorporating it in a mixture containing fuel such as peat, coal or other combustible copies of this patent may he obtained for matter adapted to retain its solid character while burning, and passing the mixture. through a chamber in which progressively increasing temperature zones are maintained for-the purpose of gasifying the volatile and non-volatile constituents of the pitch.

6. A method of utilizing pitch consisting in incorporating it in a mixture containing fuel such as peat, coal or other combustible matter adapted to retain its solid character While burning, and passing the mixture through a chamber in which progressively increasing temperature zones are maintained by partial combust'on of part of the mixture.

In testimony whereof we have signed our names to this Specification.

NILS TESTRUP. THOMAS RIGBY. Witnesses:

A. BROWN, A. P. OBHoH, J. E. DEXTER, J. Knmnr.

five cents each, by addressing the Commissioner of Iatents.

Washington, D. 0. 

